1. Field of the Invention
The invention relates to an inflatable thermal pad. With greater particularly, the invention relates to an inflatable thermal pad adaptable for use in a variety of settings. More particularly still, the invention relates to an inflatable thermal pad with a top layer for receiving a person to be warmed, the pad having provision for drainage of fluid from a surface of the top layer.
2. Background
Hypothermia affects many people. Many of those for whom hypothermia goes untreated suffer a variety of adverse effects. For example, patients under general anesthesia lose the ability to regulate their own body temperature (xe2x80x9cthermoregulatexe2x80x9d) and therefore fail to maintain the normal body temperature (xe2x80x9cnormothermiaxe2x80x9d) necessary for proper physiological functioning. The inability to thermoregulate leads to a drop in body core temperature that can result in serious complications with potential for a fatal outcome. Patients that have been warmed during surgery avoid these complications. Furthermore, these actively warmed patients benefit by experiencing decreased blood and fluid loss, fewer wound infections, and better metabolization of drugs. Recent years have seen significant advances in techniques and devices for treatment and prevention of hypothermia. The Bair Huggerg family of systems and products produced and sold by Augustine Medical, Inc., the assignee of this patent application, are a pioneering example. Such products have provided tremendous benefits for the world patient population. These products are based upon warming by means that are primarily convective. In this regard, a light, flexible inflatable device is inflated with warm air and placed over a patient. Means in a bottom surface of the device expel the warm air, which bathes the patient and creates a warmed environment about the patient, thereby reducing the transfer of heat from the patient to the environment. Such devices are referred to generally as inflatable thermal blankets. Examples of such devices abound. See, for example, U.S. Pat. No. 5,300,102 assigned to Augustine Medical, Inc. The ""102 patent is incorporated herein in its entirety by this reference.
Prior to the introduction of inflatable thermal blankets, modalities for warming patients included circulating water mattresses, warmed cotton blankets, fluid infusion warming devices, and radiant heat lamps. All of these modalities have limitations and problems associated with their use. With the introduction of the inflatable thermal blanket by Augustine Medical, Inc., clinicians have been able to provide safe and effective thermal therapy to patients in a number of clinical settings, including surgery and recovery.
Healthcare institutions have realized significant benefits from the introduction of inflatable thermal blankets. When patients are actively warmed they require less recovery time in a post-operating recovery unit. This saves hospital time, labor, and money. Furthermore, patients that are warmed have a higher degree of comfort and are more likely to have positive experiences and attitudes during and after treatment. The result is a happy, cooperative patient.
While there are many benefits related to warming patients using convective means, there are also many benefits well known in the literature that are derived from cooling patients using convective means. Therefore, it should be understood that this discussion and the invention to be described may pertain to both warming and cooling.
The opportunity to aid patient well being and improve patient thermal comfort is not limited to operating rooms and recovery units. Presently, in the healthcare setting, patients undergo a variety of procedures in a variety of clinical situations that invite patient thermoregulation. Inflatable thermal blankets are used to service these various other treatment settings, including intensive care units, neonatal care units, cardiac catheterization laboratories, chemotherapy labs, and other diagnostic rooms where magnetic resonance imaging (MRI) or computed axial tomography (CAT) scans take place.
Trauma rooms often receive patients that have lost large amounts of fluid and/or blood. Such patients may be unconscious. In these cases, immediate stabilization is required to prevent an irreversible downward cascade of physiological function. These patients are often hypothermic and the degree of hypothermia has been shown to correlate with death rates. Furthermore, these patients require immediate visual and tactile access. Patients undergoing diagnostic procedures generally already suffer from increased anxiety and/or illness related to their conditions. Diagnostic facilities utilizing MRI and CAT procedures are often cold and sterile environments because of the requirements for proper equipment function. These areas have the challenge of keeping patients comfortable and quiet during what could be prolonged sessions. Chemotherapy and catheterization laboratories also serve patients that are able to move around, are conscious, and are aware of their comfort level. In all of these settings, patients are exposed to cool and ambient environments and may also be exposed to fluids that exacerbate the cooling effect of the ambient environments.
In neonatal intensive care units (NICU), clinicians require frequent and unimpeded access to very small patients. Having such access while maintaining a warm environment poses a significant challenge that has not been met to a satisfactory degree by currently available inflatable thermal blankets. One limitation of the current convective warming technology as embodied in inflatable thermal blankets is the need to attach a thermal blanket to a neonatal patient in order to provide thermal care space. Patients undergoing procedures in the NICU may be conscious and may necessarily undergo frequent repositioning. Attaching a thermal blanket over a patient in this situation is not practical. Typically, such a device is attached to a patient by tape. Newborns have highly sensitive skin. Manifestly, the repeated placement and removal of adhesive tape to the skin of newborn patients is not desirable.
As clinicians have become aware of the benefits of treating and preventing hypothermia with convective means, the limitations of currently available inflatable thermal blankets with respect to specific patients, specific procedures, and specific environments have become evident.
Our invention is an inflatable convective thermal pad adaptable for use in a variety of clinical settings. This inflatable thermal pad can be placed under a patient to accommodate the need for access to the patient. The versatile and unique design of the inflatable thermal pad also accommodates the characteristics of specific treatment sites and treatment modalities.
Preferably, our pad is placed underneath the patient to facilitate access to the patient and to accommodate various patient positions. The pad has at least two layers of material, joined at a periphery to create an inflatable article. At least one layer, preferably the top layer, is adapted to provide for the passage of air through itself so that, when the pad is inflated with an input of pressurized, warmed air, the warmed air passes from the inflatable article through the top layer. A patient disposed on the top layer is warmed by the air passing through the layer. Preferably, the at least two layers also are joined within the periphery at at least one location. At least one inflation port opening into the pad is provided for the input of pressurized, warmed air that inflates the pad. One or more drain openings or channels are provided in the top layer for draining fluid from the top layer.
One or more extensions of the pad project beyond the periphery and provide enough area to either partially cover a patient or to stabilize the pad with respect to a support surface.
Our invention solves many problems associated with warming or cooling by means of the inflatable thermal blankets of the prior art. Consider for example, a patient in a catheterization lab. The patient, while sedated, is fully conscious and able to move around. In the cardiac catheterization procedure, a clinician examines heart function by inserting a flexible catheter into the heart through a blood vessel in an extremity of the patient. A radiographic dye is injected into the catheter to provide contrast for X-rays. During this procedure, externalized fluids can cause discomfort and undesirable evaporative cooling. Our invention provides a device that is well adapted for this procedure and well suited for solving this problem. In this regard, the pad is placed on a patient support surface, with the patient being received on the upper layer when the pad is inflated with warmed air. The warm air passes through the top layer and warms the patient. The one or more drain openings on the top layer facilitate removal of externalized fluids that might otherwise accumulate between the patient and the top layer.
Accordingly, an objective of our invention is to provide an inflatable thermal pad having a layer that supports a person while assisting in regulation of the person""s core temperature by passing air through the layer of the pad on which the person is supported. A particular advantage of the invention is the ability of the pad to drain fluid from the layer during the pad""s operation. Another advantage is the provision of an extension of the pad that may serve to either to lie over the patient in order to trap air between the patient and the pad, or to attach to a patient supporting structure in order to stabilize the pad on the structure.